CHRONOBIOSIS AND ENERGETICS/METABOLISM OF AGING CORE (CEAC) (The previous Healthy Aging Physiology Core) of the Einstein Nathan Shock Center (E-NSC) serves as the major resource for E-NSC investigators who wish to evaluate physiologic function indicative of healthy aging in animals. During this period, we supported 23 investigators for 7 types of in vivo services, utilizing state-of-the-art technologies, focused mainly on metabolic assays, as well as specialty surgical procedures. We will continue to improve and provide support to an active group of investigators. While a limited number of centers also have some of these capabilities; we uniquely integrated these approaches for application in aged rodents. Recently, our Core developed and established chronobiosis, which is the chronic surgical pairing of two animals to form a single, shared circulation. The CEAC will offer intellectual expertise specific to the design, implementation and interpretation of studies targeting the understanding of energetics and metabolic consequences and mechanisms that are specific to aging. The specific aims of the CEAC are: 1) To make available to investigators, specialized measurements of whole body and tissue-specific metabolic parameters such as glucose sensitivity and insulin action in aging rodent models, 2) To advise and assist investigators in performing less invasive studies relevant to the control of glucose homeostasis 3) To provide analyses of whole body energy balance in aging rodents, using specialized metabolic chambers and probes in rats and mice. 4) To provide specialized surgical procedures in aging rodents, such as vascular catheterizations and intracerebroventricular (ICV) and hypothalamic cannulations in rats and mice. 5) To provide `sets' of chronobiosis mice and rats [young-young (Y-Y), young-old (Y-O), old-old (O-O)] and to establish a chronobiosis tissue and plasma bank, making samples available to Investigators upon request. 6) As a future development task, we will gather information from the above in order to define normative values for aging in animals that will also be relevant to human aging, and integration with other Cores and NSCs.